CHICAGO (WBBM) -- The Shedd aquarium has hosted millions of guests, shown hundreds of special exhibits, and cared for thousands of animals over the past 75 years and Granddad, the beloved Australian lungfish, has seen them all.

The Australian lungfish is the worlds oldest Aquarium fish and Monday marks its 75th anniversary at the Shedd.In 1933, the Australian government offered Granddad to Shedd as a gift during the World's Fair in Chicago.

The lungfish was the first of its kind on exhibit in the United States.

The 4-foot-long, 25-pound elder is the oldest fish at Shedd and is the longest-living fish in any aquarium in the world.

Although he has resided at the aquarium for 78 years, his exact age is still a mystery.

It's Been A Long Swim For Shedd's AmbassadorLungfish Has Been Around Since World's FairThe Chicago Tribune By Lauren R. Harrison November 11, 2008

It is no surprise that the Shedd Aquarium's new "ambassador" is a fish, but this fish has been at it for more than 75 years.

Since 1933, when Granddad, an Australian lungfish, took up residence at the aquarium, he has lured crowds of World's Fair visitors, helped establish a mentoring program and was pivotal in opening up a relationship with Australia."He's the one that started it all," said Debra Fassnacht, executive vice president of the Shedd. "He's the reason why Shedd has hosted Australian soccer teams."

Granddad celebrated his 75th anniversary at the Shedd on Monday, and aquarium officials say the 4- foot, 25-pound scaly creature is the oldest fish in any public aquarium in the worldóbut officials still don't know his real age.

The Shedd's former director, Walter H. Chute, wanting to attract visitors to the 1933 World's Fair, arranged for Granddad's relocation from the Taronga Zoo in Sydney.

Granddad is also partly responsible for establishing the Steve Irwin Fellowship, a teen mentorship program that sends a high school student interested in science to work at the Taronga Zoo.

Although Monday's event was a celebration, Granddad had all the exuberance of, well, a really old fish.

"Normally they're just really a nice slow fish," said Bill Gwozdz, a senior aquarist. "Unfortunately it makes for an unexciting feeding."

Granddad was content at the bottom of the tank as younger lungfish swam toward the top for their meal.

I have read that a lungfish (it is freshwater and found in Australia and a few other places) can live a very long life. They are the fish that burrow into the mud during a part of the year. In any event, Granddad is a Queensland Lungfish and is one interesting legacy. This is great information!